Moistener for hectographic duplicating machines



MOISTENER FOR HECTOGRAPHIC DUPLICATING MACHINES Filed March 9, 1949 F. R. BONSCH June 3, 1952 #214 072, Y C2 3% m Affor y Patented June 3, 1952 PATENT OFFICE MOIS'IENER FOR HECTOGRAPHIC DUPLI- CATING MACHINES Francois Rodolphe Bonsch, Paris, France, assignor to Block & Anderson Limited, London, England, a British company Application March 9, 1949, Serial No. 80,513

' In Great Britain March 10, 1948 7 Claims.

This invention relates to duplicating machines of the kind in which an impression is taken from a hectographic master in mirror script on to a copy sheet, the transfer being enabled by damping with a liquid which is a solvent for the hectographic ink employed in preparing the master.

In particular, the invention relates to machines in which the copy sheet is damped by passing between a damping pad, e. g., of felt, to which the damping liquid is supplied, and a rigid bar (hereinafter termed the pad surface bar) as it is fed between a pair of rollers which bring the master and the copy sheet into contact, the pad being movable towards and away from the pad surface bar to enable a copy sheet to be introduced while the pad is spaced from the'bar, the damping be- 2 sheets are fed singly to the printing couple, and the pad surface bar is secured to the rectangular bar so that its projecting limb forms a surface substantially in continuation of the feed table surface.

In an alternative embodiment of the present I invention use is made of a construction in which on one roller (hereinafter called the master drum) so as to rotate therewith, and the other roller serves as the impression roller of the printing couple, the copy sheet being drawn past the damping pad by the feed action of the printing couple. 7

The object of thepresent invention is to provide an improved pad surface bar arrangement adapted to facilitate proper damping.

According to the present invention, the pad surface bar is pivotally supported so as to be capable of pivotation about an axis lying in a plane substantially parallel to the sheet supporting surface and extending transversely to the longitudinal direction of the bar. This enables the pad surface bar to align itself with the damping pad so that substantially uniform damping pressure is obtained along the entire length of the bar. Preferably an adjustable frictional resistance is provided'so that the bar does not move too freely.

According to one embodiment of the present invention, the pad surface bar is substantially L- shaped in cross-section and is mounted with one limb against one face of a stationary rectangular bar and the other limb projecting away from the rectangular bar to form the sheet-supporting surface. The face to face contact is obtained under adjustable pressure by a bolt passing through the saidone limb and the rectangular bar and carrying a compression spring interposed between the bar and a nut in threaded engagement with the bolt. The bolt thus forms a pivot on which the pad surfacebar can swing. Conveniently the rectangular bar constitutes a support for the delivery end of a feed table over which the copy the pad surface bar is substantially T-shaped in cross-section and the upright of the T is received in a trough-like member, the pad surface bar being pivotally supported at a substantially central point, and frictional restraint being provided to prevent undesirably free movement of the pad surface bar. Alternatively the pad surface bar in both the above-mentioned embodiments may be centrally pivoted and spring loaded at one or both ends, the spring loading tending to hold it in a mean position.

Two embodiments of the invention will now be described by way of example with reference to the accompanying diagrammatic drawings, in which:

Fig. 1 is a fragmentary section at right angles to the axes of the master drum and pressure roller,

Fig. 2 is a fragmentary front view of the pad surface bar arrangement,

Fig. 3 is a sectional view of a modified pad surface bar and support,

Fig. 4 is a fragmentary front view of the pad surface bar arrangement of Fig. 3.

Referring first to Figure 1, the hectographic copying machine comprises a master drum 2 mounted on a shaft 1 and a pressure roller 4 mounted on a shaft 3 and arranged in well known manner to be urged against the drum 2 at the pressure requisite for the copying operation. The master sheet carrying in hectographic mirror script to be copied is releasably mounted on the drum 2 in known manner. To enable copies to be produced, the sheets fed singly from a feed table I I pass between a pad 5 moistened with a solvent for the hectographic ink, and a co-operating pad surface bar 6. In this way, the sheets are damped to the necessary extent. The pad 5 has to be lifted from the bar 6 to permit the leading edge of the sheet to pass to the line of contact between' porting holder is pivotally mounted at l6 and has an arm l5 carrying a roller l4 adapted to engage a cam [3. In the operative position, a spring I! urges the pad 5 against the sheet, but in the rest position of the roller 2 in which the sheet is intro- 

